Friday, 23 March 2018

Re: [7x12minilathe] Mini-Mill CNC, First Test of X-Axis.

 

All steppers, two phase and three phase are in fact a type of BLDC motor.   The term "BLDC" simply means "brushless" or that the commutation is done by something external to the motor. 

I THINK(?) one big difference between a BLDC that is intended for continuous motion and one that is intended to be stepped is the slight misalignment the stepper has between the phases.   This is a physical thing about the shape of the metal parts inside.   To make a motor step when one coil turns off and another turns on the coils must be a step size out of phase  with each other.   I think a 3-phase stepper has three coils each one 1.2 degrees ahead of the last one.

The second big difference between a BLDC for contoinous motion and for stepping is the position sensor.  There is no sensor on a stepper the ESC needs sensor input.   So no, you could not use a conventional ESC with a three phase stepper.     


I think in general three phase motors might outperform two phase motors and if you buy a 3-phas stepper together with a matching controller both made by the same factory as a set then it should work fine for you.   But notice for the same torque and speed the 3-phase solution costs way more then double.   Stepperonline has a 400 in qz motor/drive combo for $50 but the price of a 225 in oz combo 3-phase is about $100.  Double the price for less power.    Yes that is unfair the three phase unit should run smoother  but on the other hand the new 2-phas digital drivers are very good and run the motors silently.   Now that these drivers are available I wonder if there is a market for three phase steppers?



On Fri, Mar 23, 2018 at 4:49 PM, Ralph Hulslander rhulslander@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
 

Would a ESC work, are they a BLDC (Brushless DC motor).

A BLDC is essentially a 3 phase AC motor.

Ralph

On Fri, Mar 23, 2018 at 6:15 PM, Chris Albertson albertson.chris@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
 

They are three physical motors.  Look at the diagram on the top of the motor.   You would need a special three phase controller if you wanted to use these.  The more common kind of motor is two phase

On Fri, Mar 23, 2018 at 12:22 PM, Tim Iafolla iafollatim@yahoo.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
 

Chris, a question about Leadshine if you don't mind: on Ebay there are a slew of Leadshine drivers like the one you linked to; and there are also Leadshine branded stepper motors like this: 


Is there anything special about these motors that makes them work better with LS drivers, or are they standard stepper motors with a brand name?

Thanks,
Tim




On Monday, March 19, 2018, 1:17:31 PM EDT, Chris Albertson albertson.chris@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:


 

Yes those work well but the Leadshine drivers are quite a step up in both power and sophistication.   And also in price..   This s what I plan to use

It has features like the Silent Stepstick but 
  • can handle more current
  • has optical isolators in the control inputs
  • is build into a enclosure that includes a large heat sink and connectors
  • includes a 32-bit DSP 
  • in can automatically measure resistance and inductance of the motor
  • can run on up to 50 volts, although 36 is typically used.
I'm using an older version of this in the video.  The new one above is much better.

For even more money there is another class of stepper driver -- "Closed Loop.."  These have a shaft encoder on the motor and the driver sends only enough current to make the motor move as commanded.   They increase the cost by about 160% but it might be worth later.  


On Mon, Mar 19, 2018 at 8:23 AM, Malcolm Parker-Lisberg mparkerlisberg@yahoo.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
 

Chris

If 2A per stepper phase is enough you could use Silent Stepstick drivers to prevent the resonances:
<https://www.trinamic.com/ fileadmin/assets/Products/ICs_ Documents/TMC2100_datasheet. pdf>
Ebay have them mounted on a Pololu size replacement module.

Malcolm

I don't suffer from insanity I enjoy it!
Mene, mene, tekel, upharsin
The writing is on the wall.
Ha-ktovet al ha-kir

------------------------------ --------------
On Mon, 3/19/18, Chris Albertson albertson.chris@gmail..com [7x12minilathe] <7x12minilathe@yahoogroups.com > wrote:

Subject: [7x12minilathe] Mini-Mill CNC, First Test of X-Axis.
To: "7x12minilathe" <7x12minilathe@yahoogroups.com >
Date: Monday, March 19, 2018, 2:56 AM




 










Kind of a milestone with my CNC
conversion project.  I made and installed the first actual
parts.  The X-Axis now can move.
I soon as I did this fist test I
thought that someone here might want to just stop at this
step.  It makes an excellent power feed.  With no computer
or other parts I can move the X axis as slow as about
0.00015 inches per second and as fast as the entire x-axis
range in under one second.  It is very controllable.  
  
If someone wants
to make a power feed, if you had the white plastic plate, it
would be a screw driver only job as it only takes two parts
and they use existing holes.  I can supply the 3/8 thick
plastic plates at whatever they cost me to make (not much.)
  They some off the printer with M5 treads that work well
enough to held any NEMA 23 size  motor.  I did ream them
out with a tap but I think they work better if you don't
do that, they were tighter before being
tapped.
More comments
and some video in the link below.

https://albertsonchris. wordpress.com/first-tests-of- x-axis/

--

Chris Albertson
Redondo Beach,
California











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--

Chris Albertson
Redondo Beach, California




--

Chris Albertson
Redondo Beach, California





--

Chris Albertson
Redondo Beach, California

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